1. Field of the Invention
The present invention relates to a small sized inverter device with a cooling arrangement therefor which is suitable for use in an electric motor vehicle, in particular, in an electric car.
2. Conventional Art
In an electric motor vehicle, in particular, an electric car, an inverter device which uses IGBTs (Insulated Gate Bipolar Transistor) as its semiconductor switching elements is broadly employed.
For this type of inverter device demands of size reduction and cost reduction are keen. In addition, in connection with reliability thereof guarantee of more than fifteen years duration is required.
For guaranteeing the duration of such inverter device it is important to suppress the temperature rise of its constituent parts by cooling thereof.
JP-A-7-335798(1995) discloses one of conventional arts relating to cooling of semiconductor devices in which its LSI packages are cooled with coolant.
Further, JP-A-6-204370(1994) discloses a cooling structure for semiconductor devices in which while using an aluminum heat sink processed into a hollow structure as its base, semiconductor elements having heat generating property are bonded thereon via an insulating sheet and a solder.
These conventional art coolings are effective for size reduction for such semiconductor devices, but ineffective for a large power use inverter device such as for electric cars which frequency repeat acceleration and deceleration, because the connection durability at the solder member is insufficient, and it is difficult to ensure the duration more than fifteen years.